The original question was about what firearms I would carry, so...

As my primary weapon, my Ruger Mini14 (tricked out and tactical) w/ four 30rd magazines. I carry a Ciener .22LR conversion kit in my BOB.

As backup, my Glock Model 22 in .40S&W w/2 extra magazines. I have a Ciener .22LR conversion kit for the Glock in my BOB as well.

The .223/5.56mm will handle anything on the North American continent at reasonable range and with proper shot placement (head shots). Arguably, the .22LR is equally capable. The advantage of the .223 over a .22LR is that stopping power is much greater in "center of mass" shots. The .22LR may kill but unless you can reliable and consistantly make head shots iin high stress situations on moving targets, what you shot may escape or be finished eating you before it dies. (ie; If you shoot me with your .22 and I find out about it, I'll kick your butt.)

The reasons I carry the Glock in .40S&W are much the same as above.

One factor, not mentioned that I've seen, is the fact that a rifle (all scary looking with a flash hider, folding stock and long high-cap magazine) in my hands and a pistol on my hip will make any possible trouble maker in this unfamiliar urban area think at least twice about any confrontations.